Red-footed Cannibal Fly

 

I got the opportunity to go afield last Sunday (August 27, 2023) with Iris Copen and Shaun Pogacnik, two of the Midwest's best field botanists. We hit remote sites in Jackson, Lawrence, and Pike counties in southern Ohio. Plants were the main quarry, and we saw scads of cool vegetable matter, highlighted by a new state record of a particularly beautiful species, the Maryland Meadow-beauty (Rhexia mariana). Iris and Shaun had discovered it a few days prior. I'll write about that one and share photos in a later post.

We didn't ignore bugs (one should never ignore bugs) on this epic botanical foray. This beast pictured above was an entomological highlight: the Red-footed Cannibal Fly (Promachus rufipes). Savage and capable hunters, cannibal flies spot prey flying by from their perches, roar out with a loud buzzing flight, and overtake and grab the victim in an Iron Maiden death grasp with those spiny legs. I believe the one in the photo has captured a bumblebee (Bombus sp.) It then pierces the prey with a syringe-like proboscis, injecting a powerful neurotoxin that causes near instant paralysis. Other chemicals rapidly dissolve the prey's innards, which the cannibal fly sucks out through its proboscis like a ghoulish milk shake.

These big robber flies are effective predators and can take down surprisingly large prey. CLICK HERE for an apparent case of one that captured a Ruby-throated Hummingbird.

In the photo above, a pair of Red-footed Cannibal Flies mate on a Virginia Pine branch. They can actually fly when in tandem like this, and the spectacle of nearly six inches of loudly buzzing bugs shooting past one's head is enough to make an entomophobe faint.

We felt fortunate to see a number of cannibal flies on this day. Interestingly, perhaps, they were all this species. There is a very similar species, Promachus hinei, which has redder legs and it seems to be widespread and at least locally common. But all of the cannibal flies we could see well enough to identify were P. rufipes and nary a hinei was to be seen.